Computationally efficient self-consistent born approximation treatments of phonon scattering for coupled-mode space non-equilibrium Green's function

• Published in: Journal of applied physics 2011-11, Vol.110 (9), p.094517-094517-11
• Main Author: Afzalian, Aryan
• Format: Article
• Language: English
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3658809

Efficient schemes for the non-equilibrium Green's function simulation in the mode space formalism of electron-phonon scattering using the self-consistent Born approximation in nanoscale devices are presented, both using an "exact" and phenomenological Büttiker probe treatment of electron-phonon-scattering. In both cases we have generalized the expressions previously developed for the case of uncoupled mode space to coupled mode space. In the case of the phenomenological Büttiker probe treatment, we have also adapted the expressions used in the exact treatment in order to propose a new microscopic approach of phonon scattering using no analytical or average relaxation time approximations. This allows us to evaluate the accuracy and validity of the Büttiker probe assumption of the existence of a Fermi function in nanoscale devices. Our findings are that if the trends of the exact scattering are approximately reproduced by the Büttiker probe method, it seems to overestimate the on-current for a large range of devices with a channel length of a few tens of nanometers and a drain voltage higher than 100mV.